1. Technical Field
The present invention relates to a curable silicone resin composition, which is used for encapsulating optical elements, semiconductor elements, COB (Chip on Board) or used as electrical insulation coating materials. More particularly, the curable silicone resin composition is applied for encapsulating light emitting diodes (LEDs) elements.
2. Description of Related Art
Comparing to typical lighting applications, LEDs have many advantages such as small dimension, high energy efficiency, long lifetime, more safety, faster response time, pure color, no heat radiation and no toxic substance like mercury, so that LEDs are applied extensively on architectural lighting, consumer portable lighting, retail display lighting and residential lighting.
The conventional LEDs packaging structure includes a metallic frame, a LED chip on the frame and an encapsulant to protect the LEDs from external environment damages. In general, a silver layer is coated under of the metallic frame, such as lead frame, for enhancing light utilization efficiency by reflecting the emission light back to the LED chips. However when using LEDs, the sulfur in the air would permeate through the encapsulant and then into the LEDs elements so that sulfur would react with the silver layer under the frame so as to produce black hydrogen sulfide (H2S) which would decrease light emitting efficiency.